1. Field of the Invention
The present invention relates to flush valves, and more particularly, to diaphragms used in flush valves.
2. Description of the Prior Art
Flush valves in water closets, urinals, and other plumbing devices which utilize a flexible diaphragm to establish and to seal off the connection between the inlet and outlet are well-known in the art. Typically, the diaphragm is made of an elastomeric material, such as rubber, and includes a bypass, which provides fluid communication between the inlet side of the flush valve and an upper chamber of the flush valve. A typical prior art diaphragm is shown in FIG. 1 of U.S. Pat. No. 5,232,194 to Saadi et al. (hereinafter “the Saadi patent”) and is incorporated herein by reference.
The performance of prior art diaphragms varies depending on the pressure drop between the opposite sides of the diaphragm due to the bypass orifice. Specifically, a higher pressure difference across the diaphragm, such as will occur on a bottom floor of a multistory building, causes more water to pass through the flush valve for a fixed period of time when the flush valve is activated. Likewise, in a situation where there is a low pressure difference across the diaphragm, less water will flow through the flush valve when it is activated. Hence, the amount of water flowing through the flush valve is a function of the supply of water pressure to the flush valve.
It is shown then that diaphragm-type flush valves used in toilet devices, such as urinals and water closets, are conventionally used bypass orifices. Recently, there has been some interest in filtering the water passing through the bypass orifice to prevent clogging of the bypass orifice. Essentially, the bypass orifice diameter corresponds to the time of the flush valve refill cycle. Copending published U.S. patent application Ser. No. 20010028048 A1 to Verdecchia (hereinafter the “Verdecchia application”) discloses a bypass orifice for preventing the clogging of the bypass orifice and is hereby incorporated by reference. Essentially, the diameter of the bypass orifice changes during operation so that any debris clogging the bypass orifice is dislodged. More interest has been directed recently to filtering the water prior to entering the bypass orifice. This has been accomplished by providing a separate filter, which is affixed to or coacts with the diaphragm. Hence, there is a possibility of loss of the filter breaking or separating from the diaphragm. Further, a separate filter increases the number of parts required to manufacture a flush valve diaphragm assembly and increases the assembly cost of the flush valve diaphragm assembly.
Therefore, there is a need for a filter for a flush valve diaphragm that is less costly to manufacture than those known in the art.